After the market closed, Apple reported a record jump in quarterly earnings and sales, driven by strong demand for Macs, iPhones and iPads during the holiday season.

Apple shares, which were halted briefly before the announcement, rallied over 4% in after hours trading. Shares fell over 2% in during market hours Tuesday amid worries about CEO Steve Jobs' medical leave.

IBM gained 2.4% in extended trading after the company reported fourth-quarter earnings that beat analysts' estimates.

Boeing led gainers during active trading, adding 3.4% after the defense and aeronautics company said it expects to deliver its 787 Dreamliner in the third quarter of 2011. The 787, which has been plagued by delays, was previously slated for delivery in the first quarter.

"It may be that the stock was oversold enough for it to rally back, despite the disappointing news," said Bruce McCain, chief investment strategist at Key Private Bank.

In addition to Boeing, industrial stocks Alcoa (AA, Fortune 500) and Caterpillar (CAT, Fortune 500) were both up about 2%, reflecting the bullish outlook many investors have for economic growth in 2011.

"Investor sentiment is extremely positive right now," said McCain. "And that's a risky time for the market."

He said any improvement in corporate earnings or economic data will likely have a "muted effect" on stocks, while negative surprises "can torpedo the market."

Looking ahead, quarterly reports are due early Wednesday from Goldman Sachs and Wells Fargo. Investors will also take in the latest readings on housing starts and building permits before the market opens.

Markets were closed Monday due to Martin Luther King Jr. Day. On Friday, stocks ended moderately higher, with the Dow and the S&P posting their seventh straight week of gains. That's the longest weekly win streak for the Dow since the two months of consecutive gains that ended last April.

Companies: Apple reported results late Tuesday for its best-ever quarter, with revenue of $26.7 billion driven by holiday iPad and iPhone sales that were much better than forecast. Apple's profit of $6 billion also set a new record.

Apple sold 7.3 million iPads in the quarter, easily surpassing the expectations of nearly every Wall Street analyst. It also sold 16.2 million iPhones, 4.1 million Macintosh computers and 19.5 million iPods during the quarter.

Shares of Apple had been under pressure for most of the session Tuesday, after the company announced Monday that CEO and co-founder Jobs will take another leave of absence because of health problems.

Jobs' leave of absence comes two years after the Apple CEO took a six-month sabbatical, during which he received a liver transplant. While the news may weigh on Apple shares in the coming days, the slump isn't likely to last long, said Tom Winmill, portfolio manager at Midas Funds.

"This is a very short-term phenomenon," Winmill said. "Jobs is the face of Apple, so there's no question that a lot of people think Apple is a one-man band, but Apple's really anything but -- and the prior time he went on leave, it proved to be a great buying opportunity."